Modern consumer and industrial electronic systems are growing ever more complex. Electronic devices require higher density electronic components in smaller and more flexible packages. As component densities increase, technology changes are required to satisfy the demand for higher density devices with smaller feature sizes. Extreme ultraviolet lithography, also known as soft x-ray projection lithography, is a photolithographic process for the manufacture of 0.13 micron, and smaller, minimum feature size semiconductor devices.
Extreme ultraviolet light, which can generally in the 5 to 50 nanometer wavelength range, is strongly absorbed by most materials. For that reason, extreme ultraviolet systems work by reflection rather than by transmission of light. Extreme ultraviolet radiation can be projected through a series of reflective components, including mirror assemblies and mask blanks coated with a non-reflective mask pattern, and directed onto semiconductor wafers to form high density, small feature size semiconductor devices.
The reflective components of extreme ultraviolet lithography systems can include reflective multilayer coatings of materials. Because of the high power levels of the extreme ultraviolet light, the remaining non-reflected extreme ultraviolet light causes thermal heating that can degrade reflectivity of the reflective components over time and can result in limited lifetimes for the reflective components.
In view of the need for the increasingly smaller feature size of electronic components, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations, it is critical that answers be found for these problems. Additionally, the need to reduce costs, improve efficiencies and performance, and meet competitive pressures adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.